1 files changed, 111 insertions, 0 deletions
diff --git a/webrtc/video/report_block_stats.cc b/webrtc/video/report_block_stats.cc
new file mode 100644
index 0000000000..dee5662c3c
--- /dev/null
+++ b/webrtc/video/report_block_stats.cc
@@ -0,0 +1,111 @@
+/*
+ *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#include "webrtc/video/report_block_stats.h"
+
+namespace webrtc {
+
+namespace {
+int FractionLost(uint32_t num_lost_sequence_numbers,
+                 uint32_t num_sequence_numbers) {
+  if (num_sequence_numbers == 0) {
+    return 0;
+  }
+  return ((num_lost_sequence_numbers * 255) + (num_sequence_numbers / 2)) /
+      num_sequence_numbers;
+}
+}  // namespace
+
+
+// Helper class for rtcp statistics.
+ReportBlockStats::ReportBlockStats()
+    : num_sequence_numbers_(0),
+      num_lost_sequence_numbers_(0) {
+}
+
+void ReportBlockStats::Store(const RtcpStatistics& rtcp_stats,
+                             uint32_t remote_ssrc,
+                             uint32_t source_ssrc) {
+  RTCPReportBlock block;
+  block.cumulativeLost = rtcp_stats.cumulative_lost;
+  block.fractionLost = rtcp_stats.fraction_lost;
+  block.extendedHighSeqNum = rtcp_stats.extended_max_sequence_number;
+  block.jitter = rtcp_stats.jitter;
+  block.remoteSSRC = remote_ssrc;
+  block.sourceSSRC = source_ssrc;
+  uint32_t num_sequence_numbers = 0;
+  uint32_t num_lost_sequence_numbers = 0;
+  StoreAndAddPacketIncrement(
+      block, &num_sequence_numbers, &num_lost_sequence_numbers);
+}
+
+RTCPReportBlock ReportBlockStats::AggregateAndStore(
+    const ReportBlockVector& report_blocks) {
+  RTCPReportBlock aggregate;
+  if (report_blocks.empty()) {
+    return aggregate;
+  }
+  uint32_t num_sequence_numbers = 0;
+  uint32_t num_lost_sequence_numbers = 0;
+  ReportBlockVector::const_iterator report_block = report_blocks.begin();
+  for (; report_block != report_blocks.end(); ++report_block) {
+    aggregate.cumulativeLost += report_block->cumulativeLost;
+    aggregate.jitter += report_block->jitter;
+    StoreAndAddPacketIncrement(*report_block,
+                               &num_sequence_numbers,
+                               &num_lost_sequence_numbers);
+  }
+
+  if (report_blocks.size() == 1) {
+    // No aggregation needed.
+    return report_blocks[0];
+  }
+  // Fraction lost since previous report block.
+  aggregate.fractionLost =
+      FractionLost(num_lost_sequence_numbers, num_sequence_numbers);
+  aggregate.jitter = static_cast<uint32_t>(
+      (aggregate.jitter + report_blocks.size() / 2) / report_blocks.size());
+  return aggregate;
+}
+
+void ReportBlockStats::StoreAndAddPacketIncrement(
+    const RTCPReportBlock& report_block,
+    uint32_t* num_sequence_numbers,
+    uint32_t* num_lost_sequence_numbers) {
+  // Get diff with previous report block.
+  ReportBlockMap::iterator prev_report_block = prev_report_blocks_.find(
+        report_block.sourceSSRC);
+  if (prev_report_block != prev_report_blocks_.end()) {
+    int seq_num_diff = report_block.extendedHighSeqNum -
+                       prev_report_block->second.extendedHighSeqNum;
+    int cum_loss_diff = report_block.cumulativeLost -
+                        prev_report_block->second.cumulativeLost;
+    if (seq_num_diff >= 0 && cum_loss_diff >= 0) {
+      *num_sequence_numbers += seq_num_diff;
+      *num_lost_sequence_numbers += cum_loss_diff;
+      // Update total number of packets/lost packets.
+      num_sequence_numbers_ += seq_num_diff;
+      num_lost_sequence_numbers_ += cum_loss_diff;
+    }
+  }
+  // Store current report block.
+  prev_report_blocks_[report_block.sourceSSRC] = report_block;
+}
+
+int ReportBlockStats::FractionLostInPercent() const {
+  if (num_sequence_numbers_ == 0) {
+    return -1;
+  }
+  return FractionLost(
+      num_lost_sequence_numbers_, num_sequence_numbers_) * 100 / 255;
+}
+
+}  // namespace webrtc
+